Creating Column Encryption Keys

• Key owner or custodian assignment – the system security officer (SSO) must grant create encryption key permission to create keys. By default, the sso_role and the keycustodian_role have create encryption key permission.

• Whether keys should be created in a separate key database – SAP recommends that you use a separate database for keys, especially if keys are encrypted by the system encryption password.

• The number of keys needed – you can create a separate key for each encrypted column, or you can use the same key to encrypt columns across multiple tables. From a performance standpoint, encrypted columns that join with equivalent columns in other tables should share the same key. For security purposes, unrelated columns should use different keys.

create encryption key [[database.][owner].]keyname 
	[as default] [for algorithm] 
	[with 
		{[key_length num_bits] 
		[{passwd 'passwd_phrase' | passwd system_encr_passwd | 
			master key}] 
		[init_vector {null | random}]
		[pad {null | random}]
		[[no] dual_control]
	}]

• keyname – must be unique in the user’s table, view, and procedure name space in the current database. Specify the database name if the key is in another database, and specify the owner’s name if more than one key of that name exists in the database. The default value for owner is the current user, and the default value for database is the current database. Only the system security officer can create keys for other users.

  Note: You cannot create temporary key names that start with “#”.

• as default – allows the system security officer or key custodian to create a database default key for encryption. This enables the table creator to specify encryption without using a keyname on create table, alter table, and select into. SAP ASE uses the default key from the same database. The default key may be changed.

• for algorithm – Advanced Encryption Standard (AES) is the only algorithm supported. AES supports key sizes of 128, 192, and 256 bits, and a block size of 16 bytes. The block size is the number of bytes in an encryption unit. Large data is subdivided for encryption.

• keylength num_bits – the size, in bits, of the key to be created. For AES, valid key lengths are 128, 192, and 256 bits. The default keylength is 128 bits.

• passwd password_phrase – indicates to ASE to protect the CEK using the user password password_phrase, which can be a quoted alphanumeric string up to 255 bytes in length.

• passwd system_encr_passwd – indicates to ASE to protect the CEK using the system encryption password.

• master key – indicates to ASE to protect the CEK using the master key. By default, SAP ASE uses the master key (if it exists) to protect column encryption keys.

• init_vector

  • random – specifies use of an initialization vector during encryption. When an initialization vector is used by the encryption algorithm, the cipher text of two identical pieces of plain text are different, which prevents detection of data patterns. Using an initialization vector can add to the security of your data.

    Use of an initialization vector implies using a cipher-block chaining (CBC) mode of encryption, where each block of data is combined with the previous block before encryption, with the first block being combined with the initialization vector.

    However, initialization vectors have some performance implications. You can create indexes and optimize joins and searches only on columns where the encryption key does not specify an initialization vector.

  • null – omits the use of an initialization vector when encrypting. This makes the column suitable for supporting an index.

    The default is to use an initialization vector, that is, init_vector random.

    Setting init_vector null implies the electronic codebook (ECB) mode, where each block of data is encrypted independently.

    To encrypt one column using an initialization vector and another column without using an initialization vector, create two separate keys—one that specifies use of an initialization vector and another that specifies no initialization vector.

• pad

  • null – the default, omits random padding of data.

    You cannot use padding if the column must support an index.

  • random – data is automatically padded with random bytes before encryption. You can use padding instead of an initialization vector to randomize the cipher text. Padding is suitable only for columns whose plain text length is less than half the block length. For the AES algorithm the block length is 16 bytes.

• dual control – indicates whether the new key must be encrypted using dual control. By default, dual control is not configured.